mm: mprotect: convert to folio_can_map_prot_numa()

The prot_numa_skip() naming is not good since it updates the folio access
time except checking whether to skip prot NUMA, so rename it to
folio_can_map_prot_numa(), and cleanup it a bit, remove ret by directly
return value instead of goto style.

Adding a new helper vma_is_single_threaded_private() to check whether it's
a single threaded private VMA, and make folio_can_map_prot_numa() a
non-static function so that they could be reused in change_huge_pmd(),
since folio_can_map_prot_numa() will be shared in different paths, let's
move it near change_prot_numa() in mempolicy.c.

Link: https://lkml.kernel.org/r/20251023113737.3572790-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/mm/internal.h b/mm/internal.h
index e623c8103358..56a9a714709a 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1378,6 +1378,26 @@ void vunmap_range_noflush(unsigned long start, unsigned long end);
 
 void __vunmap_range_noflush(unsigned long start, unsigned long end);
 
+static inline bool vma_is_single_threaded_private(struct vm_area_struct *vma)
+{
+	if (vma->vm_flags & VM_SHARED)
+		return false;
+
+	return atomic_read(&vma->vm_mm->mm_users) == 1;
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+bool folio_can_map_prot_numa(struct folio *folio, struct vm_area_struct *vma,
+		bool is_private_single_threaded);
+
+#else
+static inline bool folio_can_map_prot_numa(struct folio *folio,
+		struct vm_area_struct *vma, bool is_private_single_threaded)
+{
+	return false;
+}
+#endif
+
 int numa_migrate_check(struct folio *folio, struct vm_fault *vmf,
 		      unsigned long addr, int *flags, bool writable,
 		      int *last_cpupid);